A. Technical Field
The present invention relates to a novel unsaturated carboxylate and its production process and use.
B. Background Art
Hitherto, unsaturated carboxylates which have an unsaturated group or hydroxyl group in moieties derived from alcohol components of the esters are widely used for purposes of such as paints and crosslinking agents.
Allyl methacrylate is known as an example of the unsaturated carboxylates which have the unsaturated group. However, allyl methacrylate has a nonsubstituted allyl group which is highly reactive. Therefore, allyl methacrylate undergoes gelation in polymerization reactions so easily as not to fit into use for the purpose of post-crosslinking. Incidentally, herein the nonsubstituted allyl group means an allyl group in which only hydrogen atoms are bonded to all carbon atoms.
On the other hand, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate are known as examples of the unsaturated carboxylates which have the hydroxyl group. These can, for example, be treated by polymerizing their unsaturated carboxylic acid moieties and then crosslinking their hydroxyl group moieties using such as diisocyanates. However, such a treatment can be carried out only in the case where the reactivity of the hydroxyl group is available, therefore their applicable uses are naturally limited.
Unsaturated carboxylates having both an allylic unsaturated group and a hydroxyl group are disclosed as those for which the crosslinking methods can be expected to widely be selected. For example, British Patent No. 1407813 proposes a compound obtained by a reaction of methacrylic acid with allyl glycidyl ether. However, this compound also has the nonsubstituted allyl group and therefore has the same problems as those mentioned above.
A compound which is obtained by causing an unsaturated oxirane to react instead of the above-mentioned allyl glycidyl ether is also proposed. For example, Japanese Patent No. 2774122 and German Patent No. 4429690 propose processes for synthesizing a carboxylate having a carbon-carbon unsaturated group by carrying out a reaction of a carboxylic acid with an unsaturated oxirane. However, as to these processes, the carbon-carbon unsaturated group is directly bonded to a carbon atom of the oxirane ring, therefore the addition reaction of the carboxylic acid runs not only by 1,2-addition reaction, but also by 1,4-addition reaction simultaneously therewith. A carboxylate resultant from this 1,4-addition reaction has a rearranged inner olefin structure in its oxirane-derived moiety and is therefore so much low reactive as not to be fit for purposes of such as crosslinking. Furthermore, according to J. Chem. Soc. Chem. Comm., (1972) p. 491 and J. Am. Chem. Soc., (1953) vol. 75, p. 3496, it is known that if Lewis acids such as rhodium complexes and boron trifluoride are used, an rearrangement of the unsaturated oxirane itself easily arises to form an unsaturated aldehyde or ketone.
On the other hand, JP-A-032721/1993 discloses a vinyl-group-containing unsaturated carboxylate composition which is obtained by a process including the step of carrying out a reaction of a compound having one or more vinyl groups and one epoxy group per molecule with an unsaturated carboxylic acid. However, this process produces not only a 1-mol adduct, but also a large amount of multiple-mol adducts, wherein the 1-mol adduct is a product by addition of 1 mol of the compound having one or more vinyl groups and one epoxy group per molecule to the unsaturated carboxylic acid, and wherein the multiple-mol adducts are products by addition of at least 2 mol of the compound having one or more vinyl groups and one epoxy group per molecule to the unsaturated carboxylic acid, therefore the resultant unsaturated carboxylate composition is a mixture containing the multiple-mol adducts in a high ratio. These multiple-mol adducts have the disadvantage, for example, of giving higher viscosity and more easily gelling than the 1-mol adduct. Therefore, the unsaturated carboxylate composition containing the multiple-mol adducts in a high ratio, as disclosed in the above publication, is difficult to practically use according to uses. Furthermore, the above publication does not specifically describe the structure of the unsaturated carboxylate or the production ratio between the above 1-mol and multiple-mol adducts in the unsaturated carboxylate composition.
A. Object of the Invention
An object of the present invention is to provide: an unsaturated carboxylate which has both an unsaturated group and a hydroxyl group, and is applicable to a wide range of crosslinking processes, and has moderate polymerizability, and has a novel specific structure; a production process which enables to obtain this unsaturated carboxylate without causing the rearrangement of the carbon-carbon unsaturated bond of the raw unsaturated oxirane, and gives a high production ratio of unsaturated carboxylate that is a product by addition of 1 mol of the unsaturated oxirane to the unsaturated carboxylic acid (such an unsaturated carboxylate might herein be referred to simply as xe2x80x9c1-mol adductxe2x80x9d); and a radical-curable resin composition containing this unsaturated carboxylate.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above-mentioned problems. As a result, they have completed the present invention by finding that if the unsaturated carboxylate possesses two unsaturated groups having different reactivities as well as a hydroxyl group formed by ring-opening of an oxirane ring wherein, of the unsaturated groups, the unsaturated group in the alcohol component moiety of the ester is a substituted allyl group or a homoallyl group, then such an unsaturated carboxylate displays moderate polymerizability and is applicable to a wide range of crosslinking processes, and further that if at least one catalyst selected from the group consisting of chromium compounds, manganese compounds, iron compounds, nickel compounds, zinc compounds, silver compounds, tin compounds, neodymium compounds, and lead compounds is used in a reaction between an unsaturated oxirane having a specific structure and an unsaturated carboxylic acid having a specific structure, then the rearrangement of the carbon-carbon unsaturated bond of the raw unsaturated oxirane can be inhibited, and further the 1-mol adduct can efficiently be obtained.
Namely, an unsaturated carboxylate, according to the present invention, is represented by the following general formula (1): 
wherein:
R1 and R2 independently of each other represent a hydrogen atom or an organic residue;
R3 represents a hydrogen atom, a methyl group, or an organic residue other than the methyl group;
n is an integer of not smaller than 1; and
X represents: 
wherein:
R4 to R9 independently of each other represent a hydrogen atom or an alkyl group;
wherein the ratio of a 1-mol adduct of n=1 in the general formula (1) to the total of a 2-mol adduct of n=2 in the general formula (1) and a 3-mol adduct of n=3 in the general formula (1) satisfies the following inequality:
(1-mol adduct)/{(2-mol adduct)+(3-mol adduct)}xe2x89xa71(molar ratio). 
A production process for an unsaturated carboxylate, according to the present invention, comprises the step of carrying out a reaction of an unsaturated carboxylic acid of general formula (2) below with an unsaturated oxirane of general formula (3) below using at least one catalyst selected from the group consisting of chromium compounds, manganese compounds, iron compounds, nickel compounds, zinc compounds, silver compounds, tin compounds, neodymium compounds, and lead compounds,
wherein the general formula (2) is: 
wherein:
R1 and R2 independently of each other represent a hydrogen atom or an organic residue; and
R3 represents a hydrogen atom, a methyl group, or an organic residue other than the methyl group;
and wherein the general formula (3) is: 
wherein:
R4 to R9 independently of each other represent a hydrogen atom or an alkyl group.
A radical-curable resin composition, according to the present invention, comprises a radical-curable resin and further comprises at least the above unsaturated carboxylate according to the present invention as a reactive diluent.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.